Certain species of birds are protected under the Migratory Bird Treaty Act of 1918, which in turn is Federal Law in Mexico, the United States of America and Canada. Historically, the species governed by these laws migrated along flight paths with a change in seasons. Several events have affected how man and these birds have interacted. For example, when DDT (dichlorodiphenyltrichloroethane) was banned in the 1970s, its negative effect to bird eggshells was eliminated and threatened bird populations were no longer facing decimation. Additionally, natural predation from animals such as foxes, coyotes and wolves has gradually reduced owing to population declines of these predators, in part due to human expansion on lands they previously habituated. The human expansion has also affected the availability of suitable habitats for birds resulting in the significant presence of birds in urban areas. Further, a general trend in warming temperatures has increased the access to winter food supplies, which has altered the migratory behaviour of many bird species.
The net effect of the protective laws remaining in force, coupled with the above changes in migration, the availability of habitats, and the decline in predators, has resulted in increases in the populations of certain species of birds, including herbivore fowl, and in particular, herbivore waterfowl. For many bird species, these changes have also resulted in an increase in conflicts between man and bird. For example, many species of birds, in particular herbivore fowl, are attracted to areas of shortly mowed grass that allows the fowl to feed on the turf. More particularly, herbivore waterfowl are attracted to areas of shortly mowed grass that are adjacent to, and/or have easy access to, bodies of water, such as ponds and lakes, that provide both a plentiful source of food (the grassy area) and ready means of escape from predators (the body of water). This is particularly the case during seasons where the fowl are molting and have lost their flight feathers and/or are raising newly hatched young that are not yet capable of flight. In either circumstance, the waterfowl are prevented from taking to the air in order to escape predators and rely upon water as a safe refuge from ground-based predators for themselves and their families.
With the gradual increase in herbivore fowl populations, and in particular herbivore waterfowl populations such as Canada geese, there have been increased incidences of negative interaction between some of these species and man, in particular on crops, parklands, golf courses and with aircraft. These interactions range in severity from being a nuisance to being extremely costly, or even deadly in the case of fowl congregating in aircraft flight paths. At the same time, government programs for population control of bird species have been reduced. Many government departments of natural resources in the past had budgets in place for egg addling, however, many of these have been eliminated or reduced in recent years allowing for less restriction in the growth of the bird populations.
Current methods used for controlling bird populations are directed to both lethal and non-lethal forms of control, and in particular to the use of non-lethal harassment. These methods have been summarized in numerous resources. For example, the Canadian Wildlife Service of Environment Canada has prepared a 2010 handbook for the management and population control of Canada and Cackling Geese (see Handbook, Canada and Cackling Geese: Management and Population Control in Southern Canada”; Canadian Wildlife Service, Environment Canada; Cat. no.: CW66-283/2010E-PDF). The report notes that once geese become established in an area, it can be difficult to make them leave, but that their numbers can be controlled by both non-lethal and lethal management techniques. Non-lethal management techniques that do not require permits include: stopping supplemental feeding, landscape modification, barriers, modification of lawn grass (through grass length, grass type and the use of repellents), scaring/hazing (for example, propane cannons, horns and sirens; lights and lasers; distress tapes; flagging tape and streamers; balloons and kites; scarecrows; motion-activated streamers; and dogs). Non-lethal scare techniques requiring a permit include the use of a firearm (including cracker shells, screamers and bangers), aircraft and raptors. The removal/relocation of geese also requires a permit. Lethal management techniques include hunting, egg sterilization/destruction, and lethal removal. The report also notes that providing alternative feeding areas with plants that geese prefer to eat will enhance the effectiveness of most hazing and habitat manipulation techniques.
In addition to terrorizing the geese, these deterrent methods can often annoy humans (particularly noise and light-related harassment techniques) and often require the modification of landscapes in undesirable ways by saturating grassy areas with chemical repellents, allowing grass to grow to longer lengths, erecting barriers that impede human traffic as well as waterfowl traffic, and the display of visual deterrents that can be unsightly in a natural environment. While the provision of alternative feeding areas is stated to enhance the effectiveness of most hazing techniques, providing a suitable area is often impractical in practice. In addition to requiring a large area of space that is desirable for human use, in order to be effective this technique requires both the extreme application of harassment/hazing techniques in the area in which geese are not desired to make the area as unattractive as possible, and extreme efforts to make the alternative feeding area sufficiently attractive to the geese. However, the efforts to deter and attract geese will work equally well on humans, who will suffer the effects of the harassment techniques and also be drawn to the alternative feeding areas which provide large, well-kept lawns and open access to water.
With respect to the use of chemical repellents aimed at making grass or other vegetation unpalatable, the most commonly used repellents are comprised of methyl anthranilate (for example, sold as REJEX-IT®), a substance that is naturally occurring in grapes and used as a food additive for humans, but which renders the grass unpalatably bitter to fowl. A second type of repellent that is available is anthraquinone-based (for example, sold as GOOSECHASE®), which is also safe for humans but is unpalatable and causes a feeling of digestive irritation for geese. However, the application of repellents over large grassy areas is costly and requires re-application after rains or irrigation, as well as after the grass is mowed, in order to maintain effectiveness. Moreover, the widespread spraying of chemicals is not desirable in recreational areas. Thus, for areas with maintained lawns, such as parks, lawns and golf courses, the use of repellents is generally costly and ineffective as a long-term solution for the control of nuisance herbivore fowl populations, and in particular herbivore waterfowl populations such as Canada geese.
Ultimately, methods involving harassment prove to be ineffective in the long term for one primary reason—the bird's need to survive trumps mankind's desire and his allowable resources to eliminate them. The herbivore fowl, and in particular herbivore waterfowl such as Canada geese, are eventually harassed to the point where there are no acceptable feeding areas available in a given location or they become aware that the harassment techniques, while annoying, do not involve real danger. In either event, the herbivore fowl will soon return to areas in which their presence is not desired.
Owing to the lack of long-term effect, and despite the knowledge and availability of various methods of controlling the location in which nuisance herbivore fowl populations congregate, including the use of repellents, the use of alternative feeding areas, and their combination, there remains significant problems in the effective application of these methods. As a result, there is a need for an improved method and means of implementing said method, to control the manner in which herbivore fowl populations congregate that dissuades the fowl from congregating in areas where their presence is not desired and encourages the fowl to congregate in alternative areas in which their presence can be tolerated.